/*
 * Ball.java
 *
 * Created on July 9, 2004, 11:38 AM
 */

/**
 *
 * @author  levenick
 */
import java.awt.*;
public class Molecule extends FilledCircle {
    private int HT=MoleculeFrame.HT;
    private int WIDTH=MoleculeFrame.WIDTH;
    private double ELASTICITY=1.0;
     
    public static int GRAVITY=1;
    
    private int vx, vy;
    //private int nuX=100, nuY=100;
    
    /** Creates a new instance of Ball */
    public Molecule() {
    }
    
    public Molecule(int x, int y, int r, Color c) {
        super(x,y,r,c);
    }
    
    public Molecule(int x, int y, int r, Color c, int vx, int vy) {
        this(x,y,r,c);
        this.vx = vx;
        this.vy = vy;
    }
    
    private boolean willHitWall() {
        return willHitSide() || willHitTopOrBottom();
    }
    
    private boolean willHitTopOrBottom() {
        if (vy > 0) {
            return vy >= distanceToBottom();
        }
        else {
            return -vy >= distanceToTop();
        }
    }
    
    private int distanceToBottom() {
        return HT -y -radius;
    }
    
    private int distanceToTop() {
        return y-radius;
    }
    
    private int distanceToRightWall() {
        return WIDTH - (x+radius);
    }
    
    private int distanceToLeftWall() {
        return x-radius;
    }
       
    private boolean willHitSide() {     
        if (vx > 0) {
            return vx >= distanceToRightWall();
        }
        else {
            return -vx >= distanceToLeftWall();
        }
    }
    
    public void step() {
        //System.out.println("step: y=" + y + " vy=" + vy + " r=" + radius);
        if (!willHitWall()) {
            x += vx;
            y += vy;
            if (distanceToBottom() > 0)
                vy += GRAVITY;
        }
        else bounce();
    }
    
    private void bounce() {
        if (willHitTopOrBottom())
            handleYBounce();
        if (willHitSide())
            handleXBounce();
    }
    
    private void handleYBounce() {
        if (vy >= distanceToBottom()) {
            y = HT - (vy - distanceToBottom()) - radius;  // the y-coord after this step
            vy = (int)(- (vy-1)*ELASTICITY);
        }
        else {
            y = -vy -(distanceToTop() - radius) + radius;
            vy = (int)(-vy * ELASTICITY);
        }
    }

    private void handleXBounce() {
        if (vx > 0)
            x = WIDTH - (vx - (WIDTH - x - radius)) - radius;
        else x = -vx - (x-radius) + radius;
        
        vx = (int)(-vx * ELASTICITY);
    }
        

}